The scene after a truck bomb hit an apartment building in Karachi used by the Rangers paramilitary force. Photograph: Fareed Khan/AP

A suicide bomber has smashed a truck packed with explosives into housing for a paramilitary force protecting Karachi, Pakistan's largest city, killing at least one person in the resulting blast, according to officials.

The bombing underlined deteriorating security in Karachi, the sprawling port city of 18 million people that is considered the economic heart of Pakistan but is home to armed groups like the Taliban.

One dead body had been brought to the Abbasi Shaheed hospital from the explosion early on Thursday morning, Dr Saleem Memon said.

A truck smashed into the gates of a residential apartment block where members of the Rangers security force live and at least 13 people were hurt in the blast, said Javed Odho, deputy inspector general of the Karachi police.

The Rangers are a paramilitary force that is tasked with helping Karachi police maintain security.

Pakistani television showed what appeared to be a partly burned down two-storey apartment block with a large hole in the middle. Rangers cordoned off the building to hold off journalists and bystanders.

One of the Rangers, Muhammed Farooq, said he was preparing for work when he looked out the window and saw a vehicle smash through the main gate and into the building. "Then there was a really big bang and I lost my balance and I saw a lot of smoke and then I lost consciousness," he said, speaking from the hospital.

There was no immediate claim of responsibility. Taliban militants are known to operate inside the city and have targeted security officials and buildings in the past.

Half a dozen Taliban militants attacked a major naval base in Karachi in May 2011, killing at least 10 people and destroying two US-supplied surveillance aircraft. In September 2011 a Taliban suicide bomber detonated a vehicle packed with explosives outside the home of a senior police officer tasked with cracking down on militants in Karachi. At least eight people died, although the officer survived.